The present invention relates to a membrane filter module for filtering fluids in a cross-flow in cooperation with fluid distributing heads, whereby the membrane filter module has a tubular housing and membranes in the form of a bundle disposed inside the housing. The membrane are selected from the groups consisting of tubular membranes, capillary membranes and hollow fiber membranes. The housing at both ends thereof has a first central inlet for receiving a respective end of the bundle, whereby the membranes in the end of the bundle are fixedly connected to one another, and a second inlet that, within an outer collar provided at the ends of the housing, extends in an axial direction along the end of the bundle in a sealed fashion into the interior of the housing in which the bundle is disposed.
A membrane filter module of the aforementioned kind is, for example, known from DE-PS 39 16 511.6. The membrane filter module described therein contains a bundle comprised of capillary, respectively, hollow fiber membranes and discloses an arrangement of all of the inlets to the capillary, respectively, hollow fiber membranes and to the interior of the housing at both end faces of the housing.
For the embodiment of separated inlets for the filtrate, respectively, the fluid to be filtered at either endface of the housing, the membrane filter module is provided with an inner collar which encloses a central inlet and has an outer inlet which allows access to the interior of the filter housing. The two ends of the membrane bundle are held within the two inner collars at the end faces of the filter housing and are enclosed by an elastic sealing compound or are fused in a sealed manner with a plastic material. At either end face of the filter housing the free space between the inner collar and an outer collar formed by the housing wall connects to the outside of the capillary, respectively, hollow fiber membranes.
The inner collar protrudes axially relative to the end face of the outer collar to such an extent that at least an annular sealing positioned on the outer mantle surface of the inner collar is exposed. The sealing, in cooperation with a fluid distributing head, seals the central inlet of the faces of the capillary, respectively, hollow fiber membranes relative to the outer inlet of the filter housing.
When the filter housing is made from stainless steel such a sealing arrangement, due to the varying expansion coefficients of the stainless steel housing, especially of the inner collar which receives the end of the membrane bundle, and of the ends of the bundle which are enclosed in an elastically deformable sealing compound or fused with a plastic material, may, already after the first use, show ruptures within the sealing compound or the sealing may come loose from its position at the inner collar. This results in the membrane filter module showing leaks and thus being unsuitable for further filtrations.
It is therefore an object of the present invention to solve the problem of leakage for a membrane filter module within the area of the sealing compound.